350-501 · Question #222
Refer to the exhibit. An engineer is configuring path selection on router R1 for two ASNs as shown. Which additional task must the engineer perform on Router 1 so that all outbound traffic utilizes…
The correct answer is B. Configure a high weight on the peer to ASN 4567. To influence BGP path selection for outbound traffic, attributes like Weight are used, with higher values typically indicating a preferred path.
Question
Refer to the exhibit. An engineer is configuring path selection on router R1 for two ASNs as shown. Which additional task must the engineer perform on Router 1 so that all outbound traffic utilizes the link between R1 and R3 to reach ASN 4567?
Exhibit
Options
- AConfigure a low weight on the peer to ASN 4567.
- BConfigure a high weight on the peer to ASN 4567.
- CConfigure an AS path prepend on the peer to ASN 4567.
- DConfigure a high med on the peer to ASN 4567.
How the community answered
(60 responses)- A5% (3)
- B80% (48)
- C12% (7)
- D3% (2)
Why each option
To influence BGP path selection for outbound traffic, attributes like Weight are used, with higher values typically indicating a preferred path.
Configuring a low weight would make the R1-R3 path less preferred for outbound traffic, directly contradicting the goal of utilizing that specific link.
In Cisco IOS, BGP 'weight' is the first attribute evaluated in the path selection process and is locally significant to the router. Assigning a high weight to the peer connected to the R1 and R3 link will make that path more desirable for all outbound traffic destined for ASN 4567.
AS path prepending is primarily used to influence *inbound* traffic by making an AS path appear longer to external ASes, thus discouraging them from sending traffic via that path.
MED (Multi-Exit Discriminator) is an attribute used to influence how external autonomous systems select an entry point into your AS, primarily affecting *inbound* traffic.
Concept tested: BGP path selection attributes - Weight
Source: https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13761-4.html
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